Downhole safety ball valve

ABSTRACT

A downhole ball type safety valve for installation in a well at a subsurface location to control, in a failsafe manner, the fluid flow from the well. The valve is equipped with spring means to close it automatically should the hydraulic pressure employed to hold it open drop below a predetermined level, and a means to open and releasably lock open the valve in the event it cannot be opened by the main hydraulic system.

United States Patent [1 1 Nelson 1 June 3, 1975 1 DOWNHOLE SAFETY BALLVALVE [75] Inventor: Norman A. Nelson, Houston, Tex.

[73] Assignee: FMC Corporation, San Jose, Calif.

[22] Filed: I Sept. 24, 1973 [21] Appl. No.: 400,082

[52] US. Cl. 137/495; 166/224 S; 251/58;

251/89 [51] Int. Cl E21b 33/00 [58] Field of Search 251/94, 58, 89.5,174,

[56] References Cited UNITED STATES PATENTS 3,696,868 10/1972 Taylor166/224 S 3,750,751 8/1973 Mott 137/495 X Primary ExaminerMartin P.Schwadron Assistant ExaminerRobert J. Miller Attorney, Agent, or FirmW.W. Ritt, Jr.; C. E. Tripp [5 7 ABSTRACT A downhole ball type safetyvalve for installation in a well at a subsurface location to control, ina failsafe manner, the fluid flow from the well. The valve is equippedwith spring means to close it automatically should the hydraulicpressure employed to hold it open drop below a predetermined level, anda means to open and releasably lock open the valve in the event itcannot be opened by the main hydraulic system.

7 Claims, 9 Drawing Figures PATEW B 13%: 3 ms SHEET DOWNHOLE SAFETY BALLVALVE BACKGROUND OF THE INVENTION The present invention relates todownhole safety valves for installation in fluid producing wells. andmore particularly to balltype, fail-safe flow control valves designedfor use in oil or gas well production tubing.

In order to satisfy governmental safety requirements imposed to protectthe ocean and marine life from the adverse effects of petroleum andother fluids leaking or flowing wildly from offshore wells that havebeen damaged by fire, storm, collisions, etc., it has been conventionalpractice to use storm-chokes, ball-type safety valves and other devicesin the well tubing to automatically close the tubing to fluid flow whenthe well pressure reaches a predetermined figure. However satisfactorythis equipment might be on the drawing board, in actual practicemalfunctions are not infrequent, for sand and other abrasives carried bythe oil can plug up critical passages and abrade elements designed forclose tolerances. This is especially true of such safety devices thathave been in the well for a prolonged period of time, as frequently isthe case since it is quite expensive to shut the well down, pull thedevice, service or replace it, and put the well back into production.

Many of the later safety valves are hydraulically operated, that is tosay they rely on hydraulic pressure from the surface to maintain them inopen position. Should that pressure fail, as if the hydraulic linebecomes fouled or is ruptured, the valve automatically closes and oftencannot be readily reopened.

Other problems arise when hydraulic pressure is not available to openthe valve and hold it open, as where it is desirable to pump downthrough the tubing in which the valve is located, to kill the well, orto perform other desirable tubing operations. Also it usually is best torun the valve in locked open position into the well, and then place iton the fail-safe mode, but many valves for this purpose have not beenentirely successful.

SUMMARY OF THE INVENTION Broadly considered, the present inventioncomprises a fail-safe, ball-type safety valve that normally is opened,and held open by hydraulic pressure conducted from the surface, and thatcan be opened in an emergency and releasably locked open by fluidpressure exerted from the surface down through the tubing string inwhich the valve is positioned. The valve has a ball closure element thatrotates between open and closed positions without moving longitudinallyin the valves housing, and this ball is actuated by annular controlpistons that are spring-biased towards the valves closed position, andthat can be moved to open the valve either by hydraulic line pressure ortubing string fluid. The invention further includes a floating pistonand snap ring that cooperate to open and releasablylock the valve in itsopen position, and a novel manner of unlocking is provided to restorethe valve to its original normal functioning.

Accordingly. one object of the present invention is to provide a new andsuperior downhole ball-type safety valve especially for use in offshorewells.

Another object of the present invention is to provide an improved meansfor opening an hydraulicallyoperated downhole safety valve in the eventof an emergency wherein the hydraulic supply is nonfunctional.

Another object of the present invention is to provide an improved systemfor locking a downhole safety valve in its open position.

Yet another object of the present invention is to provide an improvedmeans for releasing the lockedopen valve and restore it to its normalfunctioning mode.

The foregoing and other objects and advantages of the present inventionwill become apparent from the following description of a preferredembodiment thereof, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in elevation and insection of a downhole safety ball valve embodying the principles of thepresent invention, showing the valve incorporated in a tubing string andin its closed position.

FIG. 2 is an enlarged isometric view of the ball closure elements lowercontrol piston.

FIG. 3 is an enlarged isometric view of the valves ball closure element.

FIG. 4 is a fragmentary elevation view of the valve in closed positionwith its lower control piston in phantom.

FIG. 5 is a view like FIG. 4, but with the valve in its open position.

FIG. 6 is a view like FIG. 1, showing the valve in its open, butunlocked position.

FIG. 7 is a view like FIG. 1, but also including an override wirelineplug in position for opening the valve by fluid pressure exerted throughthe tubing string.

FIG..8 is a view like FIG. 7, showing the valve after fluid pressure hasbeen applied through the tubing string.

FIG. 9 is a view like FIG. 8, showing the valve locked open and thewireline plug removed.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference first to FIGS.1-5 of the drawings, a downhole safety ball valve 10 embodying thefeatures of the present invention generally comprises a tubular housing12, a tubular landing nipple l4 threaded at 16 into the upper end of thehousing 12 and providing a means for connecting the top of the valve toa tubing string 18, and a tubular bottom sub 20 threaded at 22 into thelower end of the housing 12 and suitably equipped to connect the tubingstrings lower portion 18a to the bottom of the valve. Upper and lowerannular seals 26, 28 in grooves around the outer surfaces of the landingnipple 14 and the bottom sub 20, respectively, function to provide afluid-tight barrier between these elements and the housing 12.

Within the housing 12 is a ball closure element 30 mounted for pivotalmovement about an axis A that is transverse to the centerline B throughthe valves flow passage 32. When the ball 30 is in its closed positionas shown in FIG. 1, it prevents flow of well fluid through the valve andthus through the tubing string 18. The ball has a bore 34 of the samediameter as that of the valves flow passage 32, so that when the ballhas been rotated about its axis A into its open' position the flow ofwell fluid through the valve is unobstructed.

Rotation of the ball 30 between its open and closed positions isaccomplished by longitudinal movement of an annular lower control piston36 (seen best in FIG. 2) that has a pair of diametrically opposed.downwardly extending legs 3611. 3611 between which the ball 30 ispositioned. As seen in FIG. I. the ball has a pair of flat. oppositelyfacing exterior surfaces 30a. 30/1 that define planes which are parallelto each other and to the axis C through the valves bore 34. Cylindricalpins 38.40 protrude outwardly from the surfaces 30a. 30]) on a commonaxis D (FIG. 1) that is offset but parallel to the axis A. and extendthrough bearing elements 42,44 that are suitably shaped to slidably fitwithin relieved areas 46.48 on the inside surfaces of the lower controlpistons legs 36a. 36/). In the assembled valve the ball is precludedfrom longitudinal movement by the upper end surface 20a of the bottomsub 20. and the lower end surface 14a of a sleeve 1412 that extendsdownwardly from the landing nipples upper section 14c. Accordingly, whenthe lower control piston 36 moves downwardly from its uppermost positionillustrated in FIG. 1, it exerts a camming-type force on the pins 38, 40and causes them to move downwardly along an arc F (FIGS. 4 and 5) fromtheir position wherein the valve is fully closed (FIG. 4) towards theirposition wherein the valve is fully open (FIG. 5). Upward movement ofthe lower control piston 36 towards the position illustrated in FIG. 1causes the pins 38. 40 to follow upwardly in the same are F. therebyrotating the ball 30 towards its closed position.

The lower control piston 36 is caused to move from its uppermostposition wherein the valve is fully closed (FIG. I) to its lowermostposition wherein the valve is fully open (FIG. 6) by hydraulic fluidconducted to the valve 10 from a surface control means (not shown)through a line 50 (FIG. I). Just below the level at which the hydraulicline 50 is connected to the valves housing 12 by a fitting 52, anannular upper control piston 54 is slidably positioned between thehousing 12 and the landing nipples sleeve section 14/). with annularseals 56 providing fluid-tight barriers between these elements. Theupper control piston 54 has a lower sleeve 541: that is threaded at 58into the lower control piston 36, so that as hydraulic fluid ispressured against the top of the upper control piston 54 this elementand the lower control piston 36 move downwardly in a ballopeningdirection.

The downward movement of the pistons 54,36 is resisted by a system ofannular wave springs 60 that surround the upper control pistons sleeve54a and extend between this pistons downwardly facing shoulder 54b andan inwardly extending annular flange 12a of the valves housing 12. Thisspring system exerts an upward bias against the control pistons 36,54.and thus when the hydraulic pressure is insufficient in the line 50.such as if the line is fouled or ruptured. the valve will automaticallyclose. a fail-safe" feature of high importance particularly when thevalve is employed in offshore wells. The valve-closing force exerted bythe spring system 60 can be varied to suit the particular conditionsunder which the valve will be operating.

When the valve 10 is in operational position in a producing well. theproduction fluid in the tubing string 18a exerts its pressure againstthe lower control piston 36 through ports 20/) in thebottom sub 20.Inner and outer annular seals 62 between the lower control piston 36.the sleeve 14/1. and the housing 12 prevent upward migration of theproduction fluid. In order to open the valve. the tubing string 18 abovethe ball is pressurcd to approximately the same pressure as theproduction pressure in the strings lower section 18a. and hydraulicfluid is exerted through the line against the upper control piston 54.When this hydraulic pressure exceeds the production pressure pluswhatever predetermined additional pressure has been desig nated. such as50 psi. the pistons 54.36 move downwardly and rotate the ball 30 to itsopen position. This 5() psi pressure is arbitrary. and can be changed toanother figure if desired.

Two of the more important features of the present invention are theprovision of an annular floating piston to open the valve 10 in theevent of an emergency. such as if the hydraulic line 50 is broken orplugged so that hydraulic pressure cannot be applied to the uppercontrol piston 36, and the provision of a normally contracted expansiblesnap ring 72 that cooperates with the piston 70 to releasably lock thevalve in its open position. As seen in FIG. 1, the floating piston 70normally resides in the annulus between the valves housing 12 and thelanding nipple's sleeve section 141;, generally above the point wherethe hydraulic fitting 52 communicates with this annulus. The piston 70has inner and outer annular fluid seals 74 that establish a fluid-tightbarrier between the piston and the adjacent surfaces of the housing 12and sleeve 14/). yet facilitate longitudinal movement of the pistonbetween its uppermost position (FIG. 1) and its lowermost position asseen in FIGS. 8 and 9. Thus a fluid-tight chamber 76 is formed betweenthe floating piston 70, the valve housing 12, the upper control piston54. and the sleeve 14/). which chamber of course expands and contractsduring movemment of the pistons 54.70.

The lower segment 70a of the floating piston 70 has an outside diameterslightly less than the inside diameter of the upward-extending axialflange 540 at the top of the upper control piston 54, so that this lowersegment 70a will fit in between this flange 54c and the sleeve 14!). Thesnap ring 72. however, has a radial thickness significantly exceedingthat of the flange 54c. so that the floating pistons lower segment 70acannot pass by the ring and move inside the flange 540 so long as thering is in its contracted condition as seen in FIG. 1. Below thehydraulic fitting 52 the housing has an inner annular groove 78 with adepth sufficient to accommodate enough of the snap ring 72 so that whenthe ring is opposite this groove the cam surface 70b of the floatingpistons lower segment 70a can cam it outwardly. i.e., expand it. intothe groove and then pass on through it into the inside of the uppercontrol pistons flange 540 until it reaches the position illustrated inFIGS. 8 and 9. Accordingly. as the floating piston 70 moves downwardlyfrom its uppermost position (FIG. I it first presses the snap ring 72against the upper end of the flange 54c and causes the upper and lowercontrol pistons 54.36 to move downwardly also. thereby rotating thevalves ball 30 to its open position. When the snap ring 72 reaches thegroove 78 it is expanded into the groove as described above, therebypreventing upward movement of the control pistons 54,36. At this pointthe valve ball 30 is fully open. and further downward movement of thefloating piston 70 places its lower segment 70a inside the ring 72.retaining it expanded in the groove 78 and thus locking the valve inopen position. as shown in FIG. 9.

In order to move the floating piston 70 downwardly to open the ball 30and lock it in open position a wireline override plug 80, such as thatdiagrammatically shown in FIGS. 7 and 8, is run into the valve byconventional wireline techniques and releasably locked into the valveslanding nipple 14 in the conventional manner, such as by means oflocking dogs 82 that are caused to expand into matching internal grooves84,86 in the nipples upper portion 14c. The plug 80 includes a packersection 88 that is actuated to establish a fluidtight seal with thesleeve 14b, and a flow passage 90 that is in flow communication at ornear its upper end (not shown) with the tubing string 18. The flowpassage 90 exits from the side of the plug 80 at a level adjacent theupper end of the sleeve 14]), and communicates with one or more lateralports 92 extending through this sleeve into the upper end of the annulusbetween it and the valves housing 12. Accordingly, when the overrideplug 80 is properly landed and locked in the landing nipple 14 and thepacker 88 set as shown in FIG. 7, fluid pressure admitted into thetubing string 18 will extend into and through the plugs passage 90 andthe valves ports 92 in the direction of the arrows in FIG. 8 to exert adownward force on the floating piston 70, thereby causing this piston tomove toward its lowermost position as illustrated in FIG. 8. The plug 80can then be removed, leaving the valve in its locked open position asshown in FIG. 9.

In order to release the locked valve (FIG. 9) and restore it to itsoriginal operating mode, hydraulic pressure is admitted through the line50 into the chamber 76. This causes the floating piston 70 to moveupwardly to its uppermost position, thereby permitting the snap ring 72to contract out of the groove 78. If the hydraulic pressure issufficiently great to prevent the released control piston 54 from movingupwardly in response to the springs 60 the valve ball 30 will remainopen, otherwise it will close and the valve 10 will be restored fullyinto the condition illustrated in FIG. 1.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention.

What is claimed is:

l. A downhole safety valve assembly for controlling the flow of wellfluids, said assembly comprising 1. a tubular housing element,

2. an inner concentric fluid-conducting sleeve element secured to andspaced from the housing element, said sleeve element forming a wellfluid flow passage through said valve assembly,

3. a ball valve for controlling flow through said flow passage,

4. a control piston slidable in the annular space between said housingand sleeve elements and having ball valve operating means at its lowerend portion,

5. spring means in said space and extending between said housing elementand said control piston for urging said control piston to its valveclosed position,

6. a floating piston in said space and above said control piston,

7. control piston retainer means slidably mounted between said pistons,

8. means cooperable with said retainer means for facilitating releasableretention of said control piston in its valve opening position by saidretainer means,

9. a port in said housing for supplying fluid under pressure directly tothe upper end of said control piston for opening said ball valve,

10. a port in said sleeve element for supplying fluid under pressuredirectly from the flow passage to the upper end of said floating pistonfor moving said control piston to its valve opening position via saidretainer means, said retainer means thereupon releasably retaining saidcontrol piston in its valve opening position, and

1 1. means on said floating piston for holding said retainer means inits control piston retaining condition.

2. The valve assembly of claim 1 wherein the floating piston is movedinto its locked position solely by application of fluid pressure throughthe flow passage and the port in the sleeve element to the upper end ofsaid floating piston.

3. The valve assembly of claim 1 wherein the ball valve is mounted inthe lower end portion of the control piston for rotation with respectthereto, and wherein said ball valve is restrained by the sleeve elementagainst upward movement in the housing element.

4. The valve assembly of claim 1 wherein the lower end of the sleeveelement includes an annular valve seat with which the ball valvecooperates to establish a fluid-tight barrier preventing flow of wellfluid through the valve assembly when said ball valve is in its closedposition.

5. The valve assembly of claim 1 wherein the retainer means comprises anormally contracted, expansible snap ring.

6. The valve assembly of claim 5 wherein the snap ring is circular incross-section configuration.

7. The valve assembly of claim 1 wherein the retainer means comprises asplit ring and a ring-receiving groove formed in one of said elements,said ring being inherently biased out of said groove, and wherein thefloating piston has means for camming said ring into

1. a tubular housing element,
 1. A downhole safety valve assembly forcontrolling the flow of well fluids, said assembly comprising
 1. Adownhole safety valve assembly for controlling the flow of well fluids,said assembly comprising
 1. a tubular housing element,
 2. an innerconcentric fluid-conducting sleeve element secured to and spaced fromthe housing element, said sleeve element forming a well fluid flowpassage through said valve assembly,
 3. a ball valve for controllingflow through said flow passage,
 4. a control piston slidable in theannular space between said housing and sleeve elements and having ballvalve operating means at its lower end portion,
 5. spring means in saidspace and extending between said housing element and said control pistonfor urging said control piston to its valve closed position,
 6. afloating piston in said space and above said control piston,
 7. controlpiston retainer means slidably mounted between said pistons,
 8. meanscooperable with said retainer means for facilitating releasableretention of said control piston in its valve opening position by saidretainer means,
 9. a port in said housing for supplying fluid underpressure directly to the upper end of said control piston for openingsaid ball valve,
 10. a port in said sleeve element for supplying fluidunder pressure directly from the flow passage to the upper end of saidfloating piston for moving said control piston to its valve openingposition via said retainer means, said retainer means thereuponreleasably retaining said control piston in its valve opening position,and
 11. means on said floating piston for holding said retainer means inits control piston retaining condition.
 2. an inner concentricfluid-conducting sleeve element secured to and spaced from the housingelement, said sleeve element forming a well fluid flow passage throughsaid valve assembly,
 2. The valve assembly of claim 1 wherein thefloating piston is moved into its locked position solely by applicationof fluid pressure through the flow passage and the port in the sleeveelement to the upper end of said floating piston.
 3. The valve assemblyof claim 1 wherein the ball valve is mounted in the lower end portion ofthe control piston for rotation with respect thereto, and wherein saidball valve is restrained by the sleeve element against upward movementin the housing element.
 3. a ball valve for controlling flow throughsaid flow passage,
 4. a control piston slidable in the annular spacebetween said housing and sleeve elements and having ball valve operatingmeans at its lower end portion,
 4. The valve assembly of claim 1 whereinthe lower end of the sleeve element includes an annular valve seat withwhich the ball valve cooperates to establish a fluid-tight barrierpreventing flow of well fluid through the valve assembly when said ballvalve is in its closed position.
 5. The valve assembly of claim 1wherein the retainer means comprises a normally contracted, expansiblesnap ring.
 5. spring means in said space and extending between saidhousing element and said control piston for urging said control pistonto its valve closed position,
 6. a floating piston in said space andabove said control piston,
 6. The valve assembly of claim 5 wherein thesnap ring is circular in cross-section configuration.
 8. meanscooperable with said retainer means for facilitating releasableretention of said control piston in its valve opening position by saidretainer means,
 9. a port in said housing for supplying fluid underpressure directly to the upper end of said control piston for openingsaid ball valve,
 10. a port in said sleeve element for supplying fluidunder pressure directly from the flow passage to the upper end of saidfloating piston for moving said control piston to its valve openingposition via said retainer means, said retainer means thereuponreleasably retaining said control piston in its valve opening position,and
 11. means on said floating piston for holding said retainer means inits control piston retaining condition.